1. Field of the Invention
The present invention relates to a method of producing an integral type steel H-sheet pile.
2. Description of the Prior Art
There has been a long-felt need of providing sheet piles having a high section modulus, water leakage preventiveness and workability due to an increase of civil engineering work for construction of revetment, quay wall, landslide protection, temporary cofferdam or the like. To meet this necessity, heretofore, there have been provided various sheet piles in which joint members are welded to steel piles and various shaped steels each having a large cross section. However, processes for separately producing the main bodies of sheet piles and joint members, and processes for welding the joint members to the main bodies of sheet piles are required for producing these sheet piles, thereby increasing production costs.
Then, there have been proposed steel sheet piles of various cross sections to be produced only by a rolling process in which the main body of sheet pile is integrally formed with joint members. Among those steel sheet piles, one which can easily have a high section modulus and can be rolled with a high efficiency is a steel sheet pile being of an H shape in cross section and having joint portions, which engage joint members of adjacent sheet piles with each other, respectively. The joint members are formed at each end of a pair of flanges opposed with respect to the center line of the H-sheet pile in cross section.
Now, as disclosed in Japanese Patent Kokai(Laid-Open) No. 11061/79 for example, the conventional method for producing steel H-sheet pile has been the method wherein a beam blank having a desirable cross section, being asymmetrical in the vertical and lateral directions is used in blooming rolling or continuous casting. Since an ordinary H-shaped beam blank cannot be utilized, a blooming rolling or continuous casting process has been required exclusively for the method, thereby presenting the disadvantages that the process is complicated and a high installation cost is required.
Furthermore, heretofore, there has been adopted a process in which a group of universal mills consisting of a roughing universal mill and a roughing sizing mill perform reciprocating rolling for a plurality of passes. However, in the conventional method, as the roughing sizing mill, two-high caliber rolls have been used, thereby presenting the disadvantages that flanges are liable to fall and the shape of joint portions is produced with low accuracy.
Since the bending of the joint portions has been performed by means of two-high caliber rolls, the disadvantage that malformation of the joint portions is liable to occur also exist.
As described above, in the method of producing the steel H-sheet pile of the prior art, there have been encountered various problems in rolling which hamper efficient and highly accurate production of the steel H-sheet pile.